Multicast and Network Setup
When setting up Multicast communication on your network, TT recommends that you:
- Conform to the guidelines listed in the section called Network Complexity and Optimization.
- Review the types of hardware that TT recommends in Network Hardware.
For a list of additional documentation on IP multicast setups, refer to .
Inter-segment Multicast Redundancy
TT recommends that you set up redundant network segments:
- In the case of IP multicast forwarding, you must configure failover redundancy at the hardware level. When a failure occurs, failover is transparent and does not require changes to network configuration.
- When using multicast domains (low-speed interconnects), you must set up two or more WAN Routers. In this setup, on startup the WAN Routers designate a primary (active) machine. This machine starts broadcasting as the primary WAN Router. If this router fails, failover occurs and multicast domains reconnect after a brief period of time. For further information on WAN Routing examples and setup, refer to the TTM 4.2.x Network Administration Manual.
You can situate WAN Routers on different network segments within the same multicast domain. However, in this case, these network segments must enable IP multicast forwarding and have a high-speed interconnect.
On a TT trading system set up for WAN Routing, every five minutes in order of sequence:
- The TTM Router daemon multicasts a subscription request on the LAN.
- All TTM Daemons on the LAN respond to the request by sending one reply with a list of subjects to which they subscribe. TTM daemons use an algorithm to stagger their responses so that they do not flood the network with data.
- As soon as the TTM Router daemon receives a response with the subscription information from a TTM Daemon, it forwards the update to its WAN Routing peer.
When a WAN Router knows the subjects to which its neighbor subscribes, the WAN Router can forward to its peer any messages sent with that subject.
If the clients on your LAN subscribe to a large number of different multicast subjects, you can see a significant spike in traffic every five minutes when the TTM Router daemon sends out its subscription request. Because the WAN Router sends a unique update message for each subscription, this traffic also affects the WAN Routers.
In a single TT multicast LAN network, one multicast carries the traffic of all the required exchanges. However, it is possible to create a network environment where some exchange Gateway traffic is located on one multicast, while other traffic is located on another (a multiple multicast environment).
A multiple multicast network is typically used in networks that contain:
- coalesced prices as well as an Autospreader SE server that connects to non-coalesced price servers.
- busy exchange price servers that could benefit from joining a dedicated multicast.
For more information about multiple multicast networks, refer to the section called Multiple Multicasts.